Red Herring.... meant to misdirect you into thinking this is a legit ad, from a girl who is making her own choice in the trade. Adds to the authenticity, in case this is meant as a sting.
PERB and some regular posters don't like seeing that question of "Why No Black Gents?" and anyone trying to answer it, so it's hard to explain why a bait would say that.....
..but if you think it's a sting, just simply text "her" and see where the conversation goes. If she starts texting about her 'real age', then I'd shut it down right away.